Visa International said its network handled more than a million transactions denominated in euros from Jan. 1, when the European currency was introduced, through April.
The value of the transactions totaled $31 million, represented 1.35% of total European volume, and has been doubling each month.
Visa found that 13% of the euro payment volume was initiated by mail, telephone, or the Internet. Almost 2% of euro transactions were performed by U.S. cardholders, primarily in France, Belgium, Germany, and Austria.
"We are not surprised at how willing U.S. travelers are to use the new currency," said Hasan Alemdar, head of the single currency unit at Visa EU, the London-based regional organization for the European Union. He said the euro appeals to people who "are accustomed to paying in one currency when they travel in the United States."